4 players- at the fartherst teleporter, the one with the STG44 near it, have one person at the window, one on the balcony looking out at the generator/bridge/courtyard. have two people at the top of the steps.

window guy- shoot the zombies!
balcony courtyard guy- shoot the zombies as they run in, or at least weaken their health
steps guys- shoot the zombies!

DOGGIES: go all the way back on the baclony, to where the mystery box is sometimes. have 2 guys go into the bottom "L", where the fence is.
Have to other guys Facing the steps with no fence in front of them. these two people should be the steps guys.

WEAPONS:
steps guys- levels 5-13, MG'S/ray gun. levels 14+ UPGRADED Guns
window guy - levels 5-15, Trench gun/ submachine gun levels 13+, UPGRADED Trench gun. a bowie doesnt hurt if you can afford it
balcony courtyard guy- levels 5-10 Grenade launcher levels 10+ panzer OR die at level 8, with 5000+ points (you will lose some points) upgrade the colt (shoots grenades

from now on: window guy: shoot the zombies!
balcony courtyard guy: KILL the zombies!
steps guys: dont let the zombies get up over the steps! you will die

at level 15, EVERYONE should have juggernog (read below for window guy exception)
if the window guy has a trench, it helps to have speed cola.
at level 11, the steps guys should have juggernog
at level 15, it helps for the steps guys to have double tap

REMEMBER: keep in contact! tell your team when you reload (im looking at the steps guys!!)
window guy, dont be afriad to ask the balcony courtayd guy for help!
if the zombies get past you steps guys, let the window guy know! which reminds me, it is good to put a bettie in the doorwary out to the small outdoor balcony where the window is.
and next to the balcony courtyard guy


TIP to buy items:
heave the window guy hold a zombie at the window. (hold [] or X to do this)

TTIP for revives: USE the MONKEY BOMB!!
EASY "perkaholics" Trophy/acheivement: the window guy can hold off on a perk till round 20 WITH good steps guys! 9I recommend an upgraded Ray gun/PPsh by round 13 if you are doing this! this is becuase they are powerful guns, with a fast reload time

3 people- take away a steps guy, or take away the balcony courtyard guy

I have made it with 4 people to 22 using this
UPDATE: I have made it 28 with 4 people using this

If you find this helpful, a thanks wont hurt!

If you are on the PS3 and want do this strat with, add me: strwrsbob

"Time for a suprise!"

Nice I also use this strategy, it's pretty good.

Me and a mate figured out this strategy yesterday, and we came to lvl 31 - just the two of us. One down at the window, and one at the top. The one at the window just spam the zombies with granades through the window (you can buy granades down there). I (window) had upgraded Ray Gun, upgraded MG-42 and Monkey Bomb, he had upgraded Ray Gun, Upgraded Wunderwaffe and Monkey Bomb.

3 players. Lvl 22. After we got through the easy rounds, we went into the hallway with the spines in the green test tubes. Leave the stairs closed. 1 person watched both windows while the other 2 watched the main entrances. If you run out of ammo you can open the stairs and run anywhere you want.

i used this strategie it works awesome, we made to round 27, one of the guys timed out so the zombies surrounded us, works awesome with 4 people with upgraded guns.